Nowadays, a variety of input and output devices for video signals transferring are widely used in personal computers (PCs), projectors, video recorders, and laser compact disc players, etc. The video information of a PC is transferring to a display (i.e. a monitor) by means of an interface. The interface can be a monochrome display adapter (MDA), a color graphic adapter (CGA), a video graphic array (VGA), or a more advanced super VGA (SVGA).
VGA is in widely use among all kinds of video adapter in that it has a high level of compatibility. A generic VGA has fifteen pins, and each pin has a definition except for three spare pins. For example, the fourth pin is defined as for transferring blue color signals, the ninth pin is defined as for transferring red color signals, and the fourteenth pin is defined as for transferring vertical sync signals. Therefore, it needs only twelve pins for transferring video information from a PC to a monitor.
A video player (or a laser compact disc player) as one kind of video output devices transfers video signals to a video receiver, e.g. television, through an RCA terminal. The RCA terminal can be used to transfer red, green, and blue color signals, but the chromaticity signals and the brightness signals are coupled altogether. In this case, the video quality will be influenced due to the coupled signals. There is a built-in output connector, however, in some video outputting devices, which can separate the chromaticity signals from the brightness signals, thus provides a higher quality of the output picture of a video device. Conventionally, it is called the "S-terminal". Referring to FIG. 1, it is a schematic diagram of a conventional S-terminal. It can be seen that the S-terminal 10 shown in FIG. 1 has four pins, the third pin 12 is used to relay chromaticity signals (the so-called "Y signal"), and the fourth pin 14 is used to relay brightness signals (the so-called "C signal"). The first pin and the second pin are reserved as grounding.
Therefore, the video signals that output from a PC or the alike are to be processed via different interfaces, and different cable connectors must be connected to different adapters. It will be more convenient to have an integrated adapter that can serve to connect related devices while using PC peripherals and other video output devices simultaneously. For example, it is possible for a projection TV to connect to a PC and a video player (or the alike) at the same time by using an integrated adapter. It's not only a convenience, but also providing a way to save space. So it is desirable to have such an integrated adapter.